Huge, politically powerful SEIU battles a small breakaway group, NUHW, in the biggest private-sector labor election since 1941. The two have traded allegations of fiscal misconduct and intimidation.

The tense scene inside the cafeteria at Kaiser Permanente's sprawling Los Angeles Medical Center illustrated the bitter, long-in-the-making battle that is about to culminate in the nation's biggest private-sector labor election since 1941.

In bright red T-shirts promoting one of two unions vying to represent Kaiser employees, a few healthcare workers stood out in the sea of white smocks at the lunch tables. Across the room, a supporter of the rival group videotaped the workers in hopes of catching them breaking any rules that limit union soliciting at the Sunset Boulevard hospital.

"It's been hostile," said Edvin Hakopian, one of the red-clad backers of the National Union of Healthcare Workers.

Starting this week, about 43,000 Kaiser employees up and down the state will choose between the giant Service Employees International Union and the pint-sized NUHW, whose leaders broke away from the larger union early last year. Balloting is by mail.

The stakes are huge, beyond the wards and clinics of the roughly 300 Kaiser locations taking part in the vote. An SEIU victory could help the 2-million-member union move past a period of turmoil that has often pitted it against labor allies and seen a change in its national stewardship with the recent departure of President Andy Stern.

If NUHW wins, experts say, it could become a significant force in the healthcare industry, labor movement and Democratic politics even as it continues its fight with SEIU in other quarters, a competition that has disheartened some activists because it is draining time and dollars from efforts to organize nonunion workers.

During Stern's 14 years at the helm of SEIU, the union grew dramatically but clashed with other labor organizations, particularly when it coveted their members. Last year, it forged a truce with the California Nurses Assn., and this summer it ended an intense feud with Unite Here, a union of mostly hotel workers. SEIU's new president, Mary Kay Henry, has pledged that the union will be a more collegial member of the labor community, although no peace overtures have been made to NUHW.

Harley Shaiken, a UC Berkeley professor who studies labor issues, said the Kaiser faceoff "is a critical election, but it's unusual in that it's a fight between two unions versus a fight over organizing new members. This is putting a lot of resources into fighting for a group that is already in a union."

The campaign has played out like a bruising political race, with heavy doses of mailers, phone canvassing and mud-slinging. SEIU has a steep advantage in money and troops; NUHW is depending in part on the loyalty its leaders banked during the years they represented the workers before the split.

NUHW contends that SEIU is run by out-of-touch elitists who cozy up to management while fattening their own paychecks. SEIU counters that the smaller group is driven by its leaders' personal lust for power.

The new union's officers launched their organization after SEIU ousted them for refusing to go along with the transfer of thousands of members of their local to another chapter, a shift they denounced as undemocratic. The Oakland-based local, known as United Healthcare Workers West, was placed in trusteeship and the conflict moved to the election front.

"We have spent the last year and a half defending our union from an organization that is trying to destroy it," said Dave Regan, an SEIU executive vice president who now heads the local.

Regan said Kaiser workers would risk losing hard-earned gains in salaries and benefits if they decided to leave SEIU, a rallying cry echoed by the union's rank-and-file supporters.

"I'd rather go with what I know," said Sophia Sims, an SEIU steward who works for Kaiser in Panorama City. She was the one videotaping the NUHW organizers at the Sunset hospital.

"We've got a contract," said La Daro Figures, a pro-SEIU worker who was sitting beside Sims. "With these [NUHW] people coming in here, there are no guarantees."

SEIU's opponents say federal law protects the terms of the contract and argue that the union has tried to frighten workers. "They'll say anything — lies," said Kaiser optician Mustafaa Tyehimba, who was among the NUHW crowd in the cafeteria.

NUHW President Sal Rosselli said that its leaders, while still with SEIU, had helped Kaiser workers land some of the best contracts in the field, packages that included fully paid health insurance and fixed pensions. "We had been building the union for over 30 years," he said.

Rosselli, the former president of the SEIU local, said it has since allowed Kaiser to eliminate jobs, reduce some pension benefits and establish an employer-employee committee with an eye on trimming health coverage. Regan said none of that is true.